As a part of power lines, power cables are widely used because of their low probability of failure, safety and reliability, and flexible outgoing lines. But once the fault, maintenance is difficult, the risk is also big, so in the maintenance, test should pay special attention.

1. Preparation before work

One type of work ticket shall be filled in for power cable power outage work, and the second type of work ticket shall be filled in for work without power outage. Before work, the relevant road map, arrangement map and drawings of concealed works should be consulted in detail. The cable name and sign must be checked in detail to see if they are consistent with those written in the work order. Work can only be started after the safety measures are correct and reliable.

2. Matters needing attention in the work

The cables to be overhauled must be identified during work.

Cables to be overhauled can be divided into 2 types:

(1) Cables with terminal head failure and obvious fault points on the surface of the cable body. This kind of fault cable, the fault signs are obvious, easy to confirm.

(2) the cable surface is not exposed to the fault point of the cable. For this type of faulty cable, in addition to checking the data and verifying the cable name, it must also be identified by a cable identifier to distinguish it from other live cables in operation, especially when there are many cables in the same section, it is particularly important to strictly distinguish the cables to be repaired from other live cables. At the same time, this can also effectively prevent the wrong cable due to the cable label hanging the wrong cable, resulting in the occurrence of the accident of the wrong broken live cable. Sawing cables must have reliable safety protection measures. Before sawing the cable, it must be confirmed that it is the cable that needs to be cut and that the cable has no electricity. Then, the cable core can be nailed with a grounded iron rod with a wooden handle (with an epoxy handle) before working. The person holding the wooden handle should wear insulating gloves and stand on the insulating pad, and special attention should be paid to ensure the good grounding of the iron solder. If you need to move the cable during work, you should be careful, do not act rashly, and prevent damage to other cables in operation. The cable head must be installed according to the process requirements to ensure the quality and avoid potential accidents. After the cable is repaired, the phase of both ends of the cable should be carefully checked, the original phase color mark should be removed first, and then the correct phase color mark should be put on to prevent the old and new phase colors from being confused.

3 Precautions for high voltage test

Cable high-voltage test should strictly comply with the "electrical safety work regulations". Even in the case of poor working conditions on site, the safety requirements can not be reduced at all. The division of labor must be clear, and the safety precautions should be arranged in detail. A closed barrier or fence shall be installed at the test site to hang out "stop, high pressure danger!" Signs and guards. In particular, the other end of the cable must also be guarded and keep communication unblocked to prevent emergencies. The test device and wiring shall meet the safety requirements, and the operation must be standardized. During the test, attention should be focused and the operator should stand on the insulating mat. When changing the press line or at the end of the test, the test power supply should be disconnected, discharged, and the high-voltage part of the high-voltage equipment should be short-circuited to ground. During the high-voltage DC test, the cable shall be discharged to the ground several times and short-circuited to ground at the end of each section or at the end of the test, before the cable can be contacted.

4 Other considerations

When opening the cable well or cable trench cover, measures should be taken to prevent traffic accidents. Fences shall be arranged around the well, with obvious warning signs and barriers to prevent vehicles from entering. At night, cable wells shall be illuminated to prevent pedestrians or vehicles from falling into the wells. Turbidite gas in the well shall be removed before entering the cable well. The workers in the well shall wear safety helmets, and take measures to prevent fire, water and falling objects from high altitude. The wellhead shall be guarded by special personnel.